Add explicit values for 'eDataType'

[grospelliergilles]

Also check that values of Arccore::ISerializer::eDataType and Arcane::eDataType are the same.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.24%. Comparing base (25f4dfe) to head (e9f081c).
Report is 4 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1828   +/-   ##
=======================================
  Coverage   70.24%   70.24%           
=======================================
  Files        2263     2263           
  Lines      162812   162812           
  Branches    18766    18766           
=======================================
+ Hits       114363   114367    +4     
+ Misses      41672    41668    -4     
  Partials     6777     6777           

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